1. Field of the Invention
The present invention relates to an improvement in a recording apparatus for use in a picture recording system, such as a facsimile, copying machine and the like.
2. Description of the Prior Art
First, the prior art in this field will be described hereinunder with specific reference to FIG. 1 which is a sectional view of a typical conventional recording apparatus. In the Figure, a cylindrical hollow member (sleeve) 1 is formed from a non-magnetic material, such as aluminum and a stainless-steel material. A magnet roll 2 is constituted by a plurality of magnets assembled in a roll-like shape. A hopper and toner are denoted by reference numerals 3 and 4, respectively. Although FIG. 1 shows one recording electrode 5, actually, a multiplicity of recording electrodes 5 are provided in a row along the direction parallel to the axis of the hollow member 1. A rear electrode and a recording medium are represented by reference numerals 6 and 7, respectively. In addition, an electronic circuit 8 is adapted to selectively apply voltage pulses between the recording electrodes 5 and the rear electrode 6.
In this apparatus, the rotation of the magnet roll 2 in the direction of an arrow A causes the toner 4 to be drawn out onto the outer peripheral surface of the hollow member 1. The toner 4 is then transported in the direction of an arrow C along the outer peripheral surface of the hollow member 1 to reach the recording electrodes 5. Under this state, voltage pulses are selectively applied between the recording electrodes 5 and the rear electrode 6 by the electronic circuit 8. Consequently, the toner particles on the recording electrodes 5 to which the voltage pulses are applied are transferred to the recording medium 7 by coulomb forces against the magnetic force exerted by the magnet roll 2, to adhere to the recording medium 7 as dots, thereby effecting a recording.
The specification of Japanese Patent Publication No. 38899/1982 discloses a recording apparatus of this type more practically. The recording apparatus shown in that specification is constructed as follows: The recording electrodes 5 are constituted by the pointed end portions of conductor patterns (leads), respectively, formed on a flexible printed circuit board, which is bonded to the hollow member 1 along the outer peripheral surface thereof so as not to interfere with the transportion of the toner. In addition, the end portions of the circuit board on the side opposite to the recording electrodes 5 are taken out to both sides of the hollow member 1 and connected to the electronic circuit 8 through connectors, respectively.
The recording apparatus constructed as above, however, has the following problems to be solved:
(a) In a recording apparatus used in a facsimile or other like system, the density (picture element density) of the recording electrodes 5 is generally required to be eight or more pieces per millimeter. However, the density of the conductor patterns that can be formed on a flexible printed circuit board is generally about three to five pieces per millimeter and it is difficult to obtain a density more than that on the grounds of production yield, because of a low mechanical strength of the board; a high moisture absorption of the board; and a poor adhesion between the board and the pattern.
(b) As the conductor patterns formed on a single flexible printed circuit board are increased in number, the production yield becomes lower. Therefore, a single flexible printed circuit board will not make it possible to obtain recording electrodes in number required for a facsimile or other like system, and it is necessary to join a multiplicity of flexible printed circuit boards together. It is, however, extremely difficult as well as costly to join a multiplicity of flexible printed circuit boards together so that the pointed end portions of their conductor patterns are arranged in a straight line, and to prevent the pitch between the adjacent conductor patterns from being nonuniform at the joints between the adjacent flexible printed circuit boards.
(c) Since the whole of the electronic circuit 8 is disposed away from the hollow member 1 and the flexible printed circuit boards are extended to the electronic circuit 8 to connect thereto, the apparatus is inevitably increased in size, and it is troublesome to handle the extended portions of the flexible printed circuit boards.